Two asteroids passed close to Earth on Monday and Tuesday, according to NASA. The asteroids were the sixth-closest flyby, passing well within the moon's orbit of Earth, just like NASA expected, though they posed no danger.

"We'll have a close but very safe pass of asteroid 2012 KP24 May 28," scientists with NASA's Asteroid Watch program warned via Twitter early last week.

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Asteroid Watch is part of the Near-Earth Object Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif. The NEO office oversees the agency's efforts to detect, track and characterize potentially dangerous asteroids or comets that could zoom close to Earth, according to Space.com.

KP24 measures approximately 69 feet (21 meters) across and it 32,000 miles (51,000 kilometers) of Earth, according to NASA. However, that's child's play compared to how close the second asteroid came, NASA said.

The second asteroid, 2012 KT42, was only discovered on Memorial Day and made its closest approach at 3:07 a.m. on Tuesday morning, according to NASA. The asteroid passed within 8,950 (14,400 kilometers) miles of Earth at that point, making it the sixth closest pass in history. For comparison, the moon is typically 240,000 miles (386,000 kilometers) away from the planet.

However, 2012 KT42 posed little threat, astronomers said. At only 16 feet (5 meters) across, it is unlikely that it would have caused any damage even if it crashed into the planet, Tony Phillips, an astronomer with NASA, told MSNBC.

"Even if it did hit, this space rock is too small to cause significant damage," he said. "It would likely disintegrate almost entirely in the atmosphere, peppering the ground below with relatively small meteorites."

Congress mandated the Spaceguard Survey in 1998, which required 90 percent of near-Earth objects, such as 2012 KT42, over 1 km in diameter to be found by 2008. As of 2011, researchers found 911 NEO's through the Spaceguard program and expect 70 more objects will be found, according to NASA.

NASA tracks every NEO that has a chance of colliding with Earth in the next 100 years. The asteroid 2012 DA14 currently has the greatest chance of impacting Earth, possibly crashing down on Feb. 16, 2020, according to NASA. The chance of it hitting, however, is very slim.